1. Field of the Invention
The present invention relates to medical procedures in which a device is inserted into a body, and more particularly concerns tracking of such device with the use of magnetic resonance signals.
2. Description of Related Art
X-ray fluoroscopes are used routinely to monitor placement of devices during diagnostic and therapeutic medical procedures. Conventional X-ray fluoroscopes are designed to minimize X-ray dosage. Nevertheless, some procedures can be very long and the accumulated X-ray dose to the subject can become significant. The long term exposure of the attending medical staff is of even greater concern since they participate in these procedures regularly. Consequently, it is desirable to reduce or eliminate the X-ray dose during these procedures.
Another limitation on the use of X-ray fluoroscopes is that the technique is projective in nature and produces a single two-dimensional image. Information concerning the depth of an object within the field-of-view is not available to the operator. It is often desirable to obtain this information during surgical procedures.
Several method of using rf signals to track a device in the body have been disclosed in U.S. Patent Applications TRACKING SYSTEM TO MONITOR THE POSITION AND ORIENTATION OF A DEVICE WITH RADIOFREQUENCY FIELD GRADIENTS Ser. No. 07/753,565 by C. Dumoulin, R. Darrow, J. Schenck and S. Souza; TRACKING SYSTEM TO MONITOR THE POSITION AND ORIENTATION OF A DEVICE WITH RADIOFREQUENCY FIELDS Ser. No. 07/753,563 by C. Dumoulin, R. Darrow, J. Schenck and P. Roemer; STEREOSCOPIC X-RAY FLUOROSCOPY SYSTEM USING RADIO FREQUENCY FIELDS by C. Dumoulin and R. Darrow; AUTOMATIC GANTRY POSITIONING FOR IMAGING SYSTEMS Ser. No. 07/753,567 by C. Dumoulin and R. Darrow; and MULTI-PLANAR X-RAY FLUOROSCOPY SYSTEM USING RADIOFREQUENCY FIELDS Ser. No. 07/753,566 by R. Darrow and C. Dumoulin all filed on Sep. 3, 1991. These method do not require the use of X-rays but employs rf transmitting and receiving apparatus to track a device in a body.
Currently, there is a need for a simple method of tracking a device in an imaging system which requires little modification to the existing system and does not require X-ray radiation for tracking.